The axolotl has extraordinary regeneration capacity compared to other vertebrates. This remarkable potential has been attributed to its life-long neoteny, characterized by the exhibition of embryonic characteristics at the adult stage. A recent study provided a detailed morphological analysis of the sperm morphology of the Ambystoma mexicanum using routine and detailed histological techniques. The primary purpose of the present study is to describe a simple and inexpensive method for evaluating the morphology of axolotl sperm. In this study, spermatophore structures were collected and spread on slides and air-dried. The slides were stained with periodic acid Schiff, toluidine blue, Masson’s trichrome, Giemsa, Spermac, and Diff-Quik dye for a morphological examination. The slides were coated with gold/palladium for a scanning electron microscopy examination. The sperm of the axolotl consisted of an elongated head, a neck, and a flagellum covered with an undulating membrane. The lengths of the midpiece, tail, and head were 8.575 µm, 356.544 µm, and 103.661 µm, respectively. In the flagellum part, the wavy membrane structure, whose function has not been explained, surrounds the tail. The data obtained from this study will constitute an important step in designing future research on the reproductive and regeneration capacity of the axolotl.

Background: Since cartilage, unlike skin, does not contain vessels, it obtains nutrition by diffusion. This reduces graft viability, resulting in problems such as reductions in size, changes in shape, and resorption of the cartilage graft in the late post-graft period. This study aimed to investigate the effects of adipose-derived mesenchymal cells and conditioned medium (CM) on cartilage graft viability. Methods: Dissections were performed 4 months after the injection of 0.5 mL of CM or 2×106 mesenchymal stem cells (MSCs) in 0.5 mL after grafting into a control group and two experimental groups (n=21 rabbits in total). Chondrocyte viability and type II collagen expression in the grafted areas were analyzed by hematoxylin-eosin staining and immunohistochemical methods, respectively. Results: In the MSC and CM groups, chondrocyte proliferation at the graft tissue incision margin (MSC: P<0.01, CM: P<0.0001), chondrocyte proliferation at the auricular cartilage incision margin (MSC: P<0.05, CM: P<0.0001), integration of the graft with the surrounding cartilage (MSC: P<0.001, CM: P<0.0001) and type II collagen expression levels (MSC: P=0.001, CM: P=0.0002) significantly increased. Conclusions Xenogenic injection of MSCs and CM contributed to new cartilage production without any tumoral effects or immune reactions. In particular, the cell-free nature of CM strengthened its potential for safe use. Since injections of MSC and CM can preserve cartilage graft viability, interest in this technique is expected to increase as long-term results from clinical studies on the subject become available.